Light source control system

ABSTRACT

A light source control system includes a plurality of light sources, and a plurality of light source control devices. The light source control devices include a plurality of main light source control devices that transmits command signals to the other light source control devices. Each main light source control device includes a collision determination circuit that determines whether data of the command signal transmitted through a bus has collided with other data, and a restoration circuit that executes a restoration operation in the case of a collision. The collision determination circuit includes an edge detection circuit that detects change timing of a signal representing the data of the command signal, an area setting circuit that sets a collision determination area in accordance with the detected change timing detected, and a collision detection circuit that detects the presence or absence of a collision in the set collision determination area.

CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosure of Japanese Patent Application No. 2016-046706 filed onMar. 10, 2016 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

The disclosure relates to a device that controls the light of anillumination device.

BACKGROUND

A light control method in which a PWM signal as a light controlinstruction signal is input to control the light of a light source inaccordance with the on-duty of the signal, or a light control method inwhich a 0 to 10 V control signal as a light control instruction signalis input to control the light of a light source in accordance with theanalog value of the signal has been known from the past.

On the other hand, as an illumination control system, a system(illumination control system) that controls an illumination device bytransmitting a signal compliant with the DALI (Digital AddressableLighting Interface) standard as a light control instruction signal hasrecently been developed mainly in Europe.

In this respect, Japanese Unexamined Patent Application Publication No.2013-4484 proposes an illumination control system compliant with theDALI standard.

SUMMARY

On the other hand, in the case where control devices serving as aplurality of masters are provided on a bus, there is a phenomenon thattransmission signals collide with each other on the bus. Accordingly, itis necessary to detect the collision because data cannot be normallytransmitted and received through the bus and the data communicationscannot be executed among the devices.

The disclosure has been made to solve the above-described problems, andan object thereof is to provide a light source control system capable ofdetecting a collision of data.

The other objects and novel features will become apparent from thedescription of the specification and the accompanying drawings.

According to an embodiment, a light source control system includes aplurality of light sources, and a plurality of light source controldevices that is provided corresponding to the light sources and isprovided communicable with each other through a bus. The light sourcecontrol devices include a plurality of main light source control devicesthat transmits command signals to the other light source controldevices. Each of the main light source control devices includes acollision determination circuit that determines whether or not data ofthe command signal transmitted through the bus has collided withanother, and a restoration circuit that executes a restoration operationin the case where the data has collided with another on the basis of thedetermination result of the collision determination circuit. Thecollision determination circuit includes an edge detection circuit thatdetects change timing of a signal representing the data of the commandsignal, an area setting circuit that sets a collision determination areain accordance with the change timing detected by the edge detectioncircuit, and a collision detection circuit that detects the presence orabsence of the collision of the data of the command signal in thecollision determination area set by the area setting circuit.

According to an embodiment, a light source control system includes anedge detection circuit that detects change timing of a signalrepresenting the data of the command signal, an area setting circuitthat sets a collision determination area in accordance with the changetiming detected by the edge detection circuit, and a collision detectioncircuit that detects the presence or absence of the collision of thedata of the command signal in the collision determination area set bythe area setting circuit, and thus the collision of the data can bedetected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram for describing a configuration of a light sourcecontrol system 1 on the basis of a first embodiment;

FIG. 2 is a diagram for describing a configuration of a controller 10and peripheral circuits thereof on the basis of the first embodiment;

FIG. 3 is a diagram for describing a configuration of a DALIcommunication interface module 4 on the basis of the first embodiment;

FIG. 4 is a diagram for describing a configuration of a collisiondetermination circuit 13 on the basis of the first embodiment;

FIG. 5A and FIG. 5B are diagrams each describing a 1-bit data waveformon the basis of the first embodiment;

FIG. 6A and FIG. 6B are diagrams each describing a method of determininga collision of 1-bit data on the basis of the first embodiment;

FIG. 7 is a flowchart for executing a collision determination process onthe basis of the first embodiment;

FIG. 8 is a flowchart for executing first collision determination andsecond collision determination of the collision determination circuit 13on the basis of the first embodiment;

FIG. 9 is a flowchart for describing a subroutine process of a countprocess on the basis of the first embodiment;

FIG. 10 is a flowchart for describing a restoration process on the basisof the first embodiment;

FIG. 11 is a diagram for describing a configuration of a collisiondetermination circuit 13# on the basis of a second embodiment;

FIG. 12 is a flowchart for executing first collision determination andsecond collision determination of the collision determination circuit13# on the basis of the second embodiment;

FIGS. 13A, 13B, 13C and 13D are diagrams each describing an example inwhich a collision has occurred in the middle of a bit on the basis of athird embodiment; and

FIG. 14 is a flowchart for describing a restoration process on the basisof the third embodiment.

DETAILED DESCRIPTION

Embodiments will be described in detail with reference to the drawings.It should be noted that the same or corresponding parts are followed bythe same signs in the drawings, and the explanations thereof will not berepeated.

First Embodiment

<A. Entire Configuration>

<a1. Configuration of Light Source Control System 1>

FIG. 1 is a diagram for describing a configuration of a light sourcecontrol system 1 on the basis of a first embodiment.

With reference to FIG. 1, the light source control system. 1 includes aplurality of light source blocks 100 and a server 2.

The server 2 is coupled to the light source blocks 100 through a busBS2.

Each of the light source blocks 100 is controlled by transmitting andreceiving a signal compliant with the DALI standard through a bus BS1.

Each of the light source blocks 100 includes a plurality of lightsources 3 and a plurality of controllers 10 provided corresponding tothe respective light sources 3. Further, each of the light source blocks100 further includes a plurality of communication interface modules 5each of which is provided between the bus BS2 and the correspondingcontroller 10 while corresponding to each of the controllers 10, and aplurality of DALI communication interface modules 4 each of which isprovided between the bus BS1 and the corresponding controller 10.

It should be noted that it is not necessary to provide the communicationinterface modules 5 and the controllers 10 on a one-to-one basis.

The bus BS1 and the bus BS2 are different from each other in thecommunication standard.

The DALI communication interface modules 4 are provided in such a mannerthat data can be transmitted and received through the bus BS2.

The controllers 10 control the light sources 3 on the basis of commandsignals for turning on or off the light sources 3 received through theDALI communication interface modules 4.

Further, the controllers 10 transmit information to the server 2 coupledto the bus BS2 through the communication interface modules 5. Further,the server 2 is provided communicable with the controllers 10 throughthe bus BS2.

It should be noted that one of the controllers 10 can be used as analternative to the server 2.

The example shows a case in which N+1 light sources 3 are provided as anexample. In addition, as a method of expressing 0-th to N-th lightsources 3, the 0-th light source 3 is expressed as “light source 3-0” asan example. The same applies to the controllers 10, the DALIcommunication interface modules 4, and the communication interfacemodules 5.

Further, in the example, described is not a configuration in which oneof the controllers 10 serves as a master and the other controllers 10serve as slaves, but a configuration in which some controllers 10 serveas masters (multi-master) and the other controllers 10 serve as slaves.

Thus, a case in which a collision of data occurs on the bus BS1 will bedescribed.

<a2. Configuration of Controller 10>

FIG. 2 is a diagram for describing a configuration of the controller 10and peripheral circuits thereof on the basis of the first embodiment.

With reference to FIG. 2, the controller 10 that is a semiconductordevice is coupled to the light source 3, the DALI communicationinterface module 4, and the communication interface module 5.

The DALI communication interface module 4 is provided communicable withthe controller 10 that is another semiconductor device through the busBS1 using a signal compliant with the DALI communication standard.

The communication interface module 5 is provided communicable with theserver 2 through the bus BS2 using, for example, Ethernet (registeredtrademark) that is different from the DALI communication standard. Itshould be noted that the connection is not limited to the wiredconnection, but wireless connection can be adopted.

The controller 10 includes a driving circuit unit 11 and a signalprocessing unit 12.

The driving circuit unit 11 drives the light source 3.

The signal processing unit 12 instructs the driving circuit unit 11 byprocessing a signal received through the DALI communication interfacemodule 4.

Further, the signal processing unit 12 includes a collisiondetermination circuit 13 that determines whether or not data hascollided with another, and a restoration circuit 14 that executes arestoration operation in the case where data has collided with anotheron the basis of the determination result of the collision determinationcircuit.

The driving circuit unit 11 executes light control such as turning on oroff the light source 3 in accordance with the instruction from thesignal processing unit 12.

Further, the signal processing unit 12 is coupled to the communicationinterface module 5, and transmits data to the server 2 if needed.

<a3. Configuration of DALI Communication Interface Module 4>

FIG. 3 is a diagram for describing a configuration of the DALIcommunication interface module 4 on the basis of the first embodiment.

With reference to FIG. 3, the DALI communication interface module 4includes a diode bridge 20, photocouplers 21 and 22, resistors 23, 24,25, 28, 29, and 31, a capacitor 26, a diode 27, a Zener diode 30, and abipolar transistor 32.

The diode bridge 20 is coupled to the bus BS1 configured using two linesand nodes N0 and N2.

A transmission terminal TP of the controller 10 is coupled to thephotocoupler 21 through the resistor 23.

The photocoupler 21 includes a light emitting diode and aphototransistor. The light emitting diode is provided between the powersupply voltage and the resistor 23. One end of the phototransistor iscoupled to a node N3. The other end thereof is coupled to a node N1through the resistor 24.

The resistor 25 is coupled between the node N2 and the node N1. Theresistor 28 is coupled to the bipolar transistor 32 in series betweenthe node N0 and the node N2. The gate electrode of the bipolartransistor 32 is coupled to the node N1. The diode 27 is providedbetween the node N3 and the node NO. The capacitor 26 is coupled betweenthe node N3 and the node N2.

The node N0 is coupled to the photocoupler 22 through the resistor 29.

The photocoupler 22 includes a light emitting diode and aphototransistor.

The anode side of the light emitting diode is coupled to the resistor29. The cathode side thereof is coupled to the Zener diode 30.

One end of the photocoupler 22 is coupled to the power supply voltage.The other end thereof is coupled to a reception terminal RP of thecontroller 10. Further, the resistor 31 is coupled between the receptionterminal RP and the grounding voltage.

In the embodiment, it is determined whether or not a collision of datahas occurred on the basis of a signal received through the DALIcommunication interface module 4.

<a4. Configuration of Collision Determination Circuit 13>

FIG. 4 is a diagram for describing a configuration of the collisiondetermination circuit 13 on the basis of the first embodiment.

With reference to FIG. 4, the collision determination circuit 13includes an edge detection circuit 301 coupled to a reception terminal,a bit boundary determination circuit 302, a time counter circuit 303, acomparison circuit 304, a register group 305, an area counter circuit306, and a collision detection circuit 307.

The edge detection circuit 301 detects the rise or fall (edge) of asignal received through the reception terminal.

The bit boundary determination circuit 302 determines whether or not theedge is an edge of a bit boundary.

The time counter circuit 303 counts time in accordance with thedetection of the edge.

The comparison circuit 304 compares the count value from the timecounter circuit 303 with a predetermined value set by the register group305. In the case where the count value is equal to or larger than thepredetermined value, the comparison circuit 304 outputs a comparisonresult signal to the area counter circuit 306.

The area counter circuit 306 increments an area counter on the basis ofthe comparison result signal from the comparison circuit 304.

The collision detection circuit 307 executes collision determination onthe basis of an area counter value from the area counter circuit 306 andan edge detection signal from the edge detection circuit 301.

In the case where it is determined that a collision has occurred byexecuting the collision determination, the collision detection circuit307 outputs a collision interruption signal.

As an example, the time counter circuit 303, the comparison circuit 304,the register group 305, and the area counter circuit 306 configure anarea setting circuit that sets a collision determination area inaccordance with change timing detected by the edge detection circuit301.

<B. Description of Collision Determination>

<b1. Data Determination>

FIG. 5A and FIG. 5B are diagrams each describing a data waveform of onebit on the basis of the first embodiment.

With reference to FIG. 5A, it is assumed that the Manchester coding isapplied to communication data compliant with the DALI standard in theexample.

Here, a data waveform in the case of data “0” is shown.

In the case of a normal waveform, shown is a data waveform falling fromthe “H” level to the “L” level around nearly the middle of a cycleperiod assigned to one bit.

In the example, when detecting a fall edge (change timing) from the “H”level to the “L” level, the data is assumed as data “0” as an example.

As similar to the above, with reference to FIG. 5B, a data waveform inthe case of data “1” is shown.

In the case of a normal waveform, shown is a data waveform rising fromthe “L” level to the “H” level around nearly the middle of a cycleperiod assigned to one bit.

In the example, when detecting a rise edge (change timing) from the “L”level to the “H” level, the data is assumed as data “1” as an example.

<b2. Collision Determination>

FIG. 6A and FIG. 6B are diagrams each describing a method of determininga collision of 1-bit data on the basis of the first embodiment.

With reference FIG. 6A, the example shows a case in which a collisionbetween the data “0” and data “1” is determined.

Since the Manchester coding is applied to the communication data, thereare two situations in which the edge corresponds to a bit boundary andthe edge represents data.

In this case, data collision determination (first collisiondetermination) in the case where the edge detected first corresponds toa bit boundary will be described.

Sections (0) to (5) are assigned. The length of each section is storedin the register group 305.

Specifically, in the case where the edge corresponds to a bit boundary,a section from the bit boundary to a timing value M is assigned to thesection (0).

A section between timing values M and N, a section between timing valuesN and O, a section between timing values O and P, a section betweentiming values P and Q, and a section subsequent to the timing value Qare assigned to the sections (1), (2), (3), (4), and (5), respectively.

The section (1) and the section (5) are destroy sections. In the casewhere the edge is detected in one of the sections, it is determined thata collision has occurred.

The section (3) is an effective section. The detection of the edge inthe section indicates data, and it is determined that no collision hasoccurred.

The sections (0), (2), and (4) are gray sections, and can be variablyset to any one of the destroy sections and the effective sections.

As an example, a case in which the gray section is set to the destroysection will be described.

With reference to FIG. 6B, data collision determination (secondcollision determination) in the case where the edge detected first is inthe middle of a bit will be described.

The example shows a case in which a collision between data “1” and data“0” is determined.

Sections (0) to (9) are assigned. The length of each section is storedin the register group 305.

Specifically, in the case where the edge corresponds to the middle of abit, a section from the middle of the bit to a timing value R isassigned to the section (0).

A section between timing values R and S, a section between timing valuesS and T, a section between timing values T and U, a section betweentiming values U and V, a section between timing values V and W, asection between timing values W and X, a section between timing values Xand Y, a section between timing values Y and Z, and a section subsequentto the timing value Z are assigned to the sections (1), (2), (3), (4),(5), (6), (7), (8), and (9), respectively.

The section (1), the section (5), and the section (9) are the destroysections. In the case where the edge is detected in one of the sections,it is determined that a collision has occurred.

The section (3) and the section (7) are the effective sections. Thedetection of the edge in one of the sections indicates data or a bitboundary, and it is determined that no collision has occurred.

The sections (0), (2), (4), (6), and (8) are the gray sections, and canbe variably set to any one of the destroy sections and the effectivesections.

As an example, a case in which the gray section is set to the destroysection will be described.

It should be noted that the timing values of the first collisiondetermination and the second collision determination are stored in theregister group 305.

<b3. Flow>

FIG. 7 is a flowchart for executing a collision determination process onthe basis of the first embodiment.

The process is a process in the collision determination circuit 13 ofthe controller 10.

With reference to FIG. 7, the collision determination circuit 13determines whether or not an edge has been detected through thereception terminal (Step S4). Specifically, the edge detection circuit301 determines whether or not an edge has been detected through thereception terminal, and outputs a detection signal to each of the bitboundary determination circuit 302, the time counter circuit 303, thearea counter circuit 306, and the collision detection circuit 307.

In Step S4, the collision determination circuit 13 maintains Step S4until the edge is detected (NO in Step S4).

In addition, in the case where the collision determination circuit 13detects the edge (YES in Step S4), it is determined that the edgecorresponds to the bit boundary or the middle of the bit (Step S6). Thebit boundary determination circuit 302 determines whether or not theedge corresponds to the bit boundary in accordance with a detectionsignal of the edge from the edge detection circuit 301. The first edgefrom the start of communications is a start bit, and thus it isdetermined that the edge corresponds to the bit boundary. Then, the flowreturns to Step S6 without performing the collision determination.

In the case where it is determined that the edge corresponds to the bitboundary in Step S6, the collision determination circuit 13 executes thefirst collision determination (Step S8).

Specifically, the collision determination in the sections (0) to (5)described using FIG. 6A is executed. The first collision determinationwill be described later.

Next, the collision determination circuit 13 determines whether or not acollision has been detected (Step S10). The collision detection circuit307 executes the first collision determination to determine whether ornot a collision has been detected.

In the case where the collision determination circuit 13 determines thatthe collision has been detected in Step S10 (YES in Step S10), thecollision interruption signal is generated (Step S12). In the case wherethe collision detection circuit 307 determines that the collision hasbeen detected, the collision interruption signal is generated. Then, theprocess is completed (end).

On the other hand, in the case where the collision determination circuit13 determines that no collision has been detected in Step S10 (NO inStep S10), the flow returns to Step S6 to execute the above-describedfirst or second collision determination.

On the other hand, in the case where the collision determination circuit13 determines that the edge corresponds to the middle of the bit in StepS6, the second collision determination is executed (Step S14).

Specifically, the collision determination in the sections (0) to (9)described using FIG. 6B is executed. The second collision determinationwill be described later.

Next, the collision determination circuit 13 determines whether or notthe collision has been detected (Step S10). The collision detectioncircuit 307 executes the second collision determination to determinewhether or not the collision has been detected.

In the case where the collision determination circuit 13 determines thatthe collision has been detected in Step S10 (YES in Step S10), thecollision interruption signal is generated (Step S12). In the case wherethe collision detection circuit 307 determines that the collision hasbeen detected, the collision interruption signal is generated. Then, theprocess is completed (end).

On the other hand, in the case where the collision determination circuit13 determines that no collision has been detected in Step S10 (NO inStep S10), the flow returns to Step S6.

FIG. 8 is a flowchart for executing the first collision determinationand the second collision determination of the collision determinationcircuit 13 on the basis of the first embodiment.

With reference to FIG. 8, a counter value is initialized (Step S20).Specifically, the time counter circuit 303 and the area counter circuit306 are initialized (reset). The value of the initialization can be setto 0.

Next, a count process is executed (Step S21). The detail of the countprocess will be described later.

Next, it is determined whether or not the edge has been detected throughthe reception terminal (Step S22). Specifically, the edge detectioncircuit 301 determines whether or not the edge has been detected throughthe reception terminal. In the case where the edge has been detected, adetection signal is output to each of the bit boundary determinationcircuit 302, the time counter circuit 303, the area counter circuit 306,and the collision detection circuit 307.

In the case where the collision determination circuit 13 determines thatno edge has been detected in Step S22 (NO in step S22), it is determinedwhether or not the area counter value is equal to or larger than themaximum value (Step S26).

In the example, the maximum value is set in each of the first collisiondetermination and the second collision determination. Specifically, inthe case of the first collision determination, the maximum value is setto “5”. Further, in the case of the second collision determination, themaximum value is set to “9”.

In the case where it is determined that the area counter value is equalto or larger than the maximum value in Step S26 (YES in Step S26), it isdetermined that the collision has been detected (Step S24).

Then, the process is completed (return).

On the other hand, in the case where it is determined that the areacounter value is smaller than the maximum value in Step S26 (NO in StepS26), the flow returns to Step S21 to continue the count process.

On the other hand, in the case where the collision determination circuit13 determines that the edge has been detected in Step S22 (YES in StepS22), it is determined whether or not the area counter value is in thedestroy section (Step S23).

In the case where it is determined that the area counter value is in thedestroy section in Step S23 (YES in Step S23), it is determined that thecollision has been detected (Step S24).

Then, the process is completed (return).

On the other hand, in the case where it is determined that the areacounter value is not in the destroy section in Step S23 (NO in StepS23), Step S24 is skipped to complete the process (return). In thiscase, the edge has been detected in the effective section, and nocollision has occurred.

For example, the detection of the edge in the section (3) in the firstcollision determination means the detection in the effective section,and no collision has occurred.

Then, it is determined that no collision has been detected in Step S10of FIG. 7, and the flow returns to Step S6 to repeat the same process.For example, in the case where the edge has been detected in the section(3) in the first collision determination, the second collisiondetermination is executed next time.

For example, the detection of the edge in the section (3) in the secondcollision determination means the detection in the effective section,and no collision has occurred.

Then, it is determined that no collision has been detected in Step S10of FIG. 7, and the flow returns to Step S6 to repeat the same process.For example, in the case where the edge has been detected in the section(3) in the second collision determination, the first collisiondetermination is executed next time.

Further, the detection of the edge in the section (7) in the secondcollision determination means the detection in the effective section,and no collision has occurred.

Then, it is determined that no collision has been detected in Step S10of FIG. 7, and the flow returns to Step S6 to repeat the same process.For example, in the case where the edge has been detected in the section(7) in the second collision determination, the second collisiondetermination is executed next time.

FIG. 9 is a flowchart for describing a subroutine process of the countprocess on the basis of the first embodiment.

With reference to FIG. 9, it is determined that a time counter value isequal to or larger than a comparison value (Step S36). The comparisoncircuit 304 compares the time counter value of the time counter circuit303 with the comparison value to determine whether or not the timecounter value is equal to or larger than the comparison value.

It should be noted that it is assumed that the initialization value ofthe comparison value is set by the register group 305. Specifically, inthe case of the first collision determination, the timing value M isset. In the case of the second collision determination, the timing valueR is set.

In the case where it is determined that the time counter value issmaller than the comparison value in Step S36 (NO in Step S36), StepsS38 and S40 are skipped to proceed to Step S41.

In Step S41, the time counter circuit 303 counts up the time countervalue.

Then, the process is completed (return).

On the other hand, in the case where it is determined that the timecounter value is equal to or larger than the comparison value in StepS36 (YES in Step S36), the area counter value is counted up (Step S38).Specifically, the comparison circuit 304 outputs a signal on the basisof the comparison result to the area counter circuit 306. The areacounter circuit 306 counts up the area counter value on the basis of thesignal on the basis of the comparison result. The initialization valueis 0 and represents the section (0).

Next, the comparison value is set (Step S40).

Specifically, the register group 305 sets the next comparison valuestored in the register group 305 to the comparison circuit 304 inresponse to the signal on the basis of the comparison result.

Next, the time counter circuit 303 counts up the time counter value inStep S41.

Then, the process is completed (return).

For example, in the case where the time counter value has reached thetiming value M, the area counter value is counted up. Namely, thesection is transited from the section (0) to the section (1). As similarto the above, in the case where the time counter value has reached thetiming value N, the area counter value is counted up. Namely, thesection is transited from the section (1) to the section (2).

It is possible to recognize the current section by the process.

Thus, in the case where the area counter value is counted up and reachesthe maximum value or larger, it can be determined that the collision hasoccurred in the first collision determination and the second collisiondetermination.

<C. Description of Restoration Process>

A restoration process in the case where a collision has occurred will bedescribed.

In the case where a collision has occurred, data cannot be normallytransmitted and received. Thus, the fact is notified to the othermasters to stop the transmission of the data.

Then, a restoration process of executing the transmission operationagain after a predetermined period elapses is executed.

FIG. 10 is a flowchart for describing the restoration process on thebasis of the first embodiment.

With reference to FIG. 10, the process is mainly executed by therestoration circuit 14 of the controller 10.

The restoration circuit 14 determines whether or not the collisioninterruption signal is present (Step S40).

Specifically, the restoration circuit 14 determines whether or not aninput of the collision interruption signal from the collisiondetermination circuit 13 is present.

In the case where the restoration circuit 14 determines that an input ofthe collision interruption signal from the collision determinationcircuit 13 is present in Step S40 (YES in Step S40), the transmission isstopped (Step S41). The restoration circuit 14 stops the transmission ofdata to the bus BS1 through the DALI communication interface module 4.

Next, the restoration circuit 14 outputs data of the “L” level to thebus BS1 through the DALI communication interface module 4 (Step S44).

Then, the restoration circuit 14 waits for a predetermined period in thestate (Step S46).

Accordingly, a collision of transmission data of the other controllers10 that are the other masters occurs, and the occurrence of thecollision of the other controllers 10 that are the other masters on thebus BS1 is detected.

Then, the same process is executed.

Next, the restoration circuit 14 outputs data of the “H” level to thebus BS1 through the DALI communication interface module 4 (Step S48).

Next, the restoration circuit 14 determines whether or not a receptionsignal from the bus BS1 through the DALI communication interface module4 is of the “H” level (Step S50).

In the case where the restoration circuit 14 determines that thereception signal is of the “H” level in Step S50 (YES in Step S50), itcan be determined that data of the “L” level has not been output fromthe other controllers 10 that are the other masters.

Then, the restoration circuit 14 executes the restoration operation(Step S54). Specifically, the transmission of data from the controller10 is started again. It should be noted that in order to suppress acollision of data with the other controllers 10 at the time of therestoration operation, the restoration operation may be started afterfurther waiting for a predetermined period.

Then, the process is completed (end).

On the other hand, in the case where the restoration circuit 14determines that the reception signal is not of the “H” level in Step S50(NO in Step S50), it can be determined that data of the “L” level hasbeen output from the other controllers 10 that are the other masters. Inthis case, the restoration circuit 14 waits until the reception signalbecomes the “H” level.

Then, the restoration circuit 14 waits until the reception signalbecomes the “H” level in Step S50. After the reception signal becomesthe “H” level, the above-described restoration operation is executed.

Then, the process is completed (end).

In the case where a collision of data with the other masters occurs, theoccurrence of the collision can be suppressed by the process by avoidinga situation in which the collision continuously occurs, and stable datacommunications can be executed.

It should be noted that the timing values are stored in the registergroup 305 in the above description of the embodiment. However, thepresent invention is not limited to the timing values, but differencevalues of the sections may be stored. Further, the timing values can bearbitrarily changed, and the sections (boundary values) can be freelyset.

Thus, the sections can be adjusted in accordance with variations in therespective light source blocks 100 and components of the light sourcecontrol system 1. Further, stable data communications can be executed byadjusting the sections in accordance with electric characteristics andaged deterioration.

Further, the example describes a method of determining an area on thebasis of the timing of detection of the edge using the area countercircuit 306. However, the section of the timing of detection of the edgecan be determined only by the time count value of the time countercircuit 303. In addition, a collision can be determined on the basis ofthe determination.

Second Embodiment

<a5. Configuration of Collision Determination Circuit 13#>

FIG. 11 is a diagram for describing a configuration of a collisiondetermination circuit 13# on the basis of a second embodiment.

With reference to FIG. 11, the collision determination circuit 13# isdifferent from the collision determination circuit 13 of FIG. 4 in thata register group 400 is provided and the collision detection circuit 307is replaced by a collision detection circuit 307#. The otherconfigurations are the same as those described in FIG. 4, and thus thedetailed explanations thereof will not be repeated.

The register group 400 is a register that can set the gray sectiondescribed in FIG. 6 to the effective section or the destroy section.

The collision detection circuit 307# executes the first collisiondetermination and second collision determination on the basis ofinformation set by the register group 400.

<b4. Flow>

FIG. 12 is a flowchart for executing the first collision determinationand second collision determination of the collision determinationcircuit 13# on the basis of the second embodiment.

The flowchart of FIG. 12 is different from that described in FIG. 8 inthat Steps S27 and S28 are added. The other flows are the same, and thusthe detailed explanations thereof will not be repeated.

In the case where it is determined that the area counter value is not inthe destroy section in Step S23 (NO in Step S23), it is determinedwhether or not the area counter value is in the gray section (Step S27).The determination can be made on the basis of the set information storedin the register group 400.

In the case where it is determined that the area counter value is not inthe gray section in Step S27 (NO in Step S27), Step S24 is skipped tocomplete the process (return). In this case, the edge has been detectedin the effective section, and no collision has occurred.

On the other hand, in the case where it is determined that the areacounter value is in the gray section in Step S27 (YES in Step S27), itis determined whether or not the gray section is the destroy section(Step S28). The determination can be made on the basis of the setinformation stored in the register group 400.

In the case where it is determined that the gray section is the destroysection in Step S28 (YES in Step S28), it is determined that thecollision has been detected (Step S24).

On the other hand, in the case where it is determined that the graysection is not the destroy section in Step S28 (NO in Step S28), StepS24 is skipped to complete the process (return). In this case, the edgeis regarded as having been detected in the effective section, and nocollision has occurred.

For example, in the case where the sections (2) and (4) are set to theeffective sections by the register group 400 in the first collisiondetermination and the edge has been detected in the sections, the edgehas been detected in the effective section, and no collision hasoccurred.

Then, it is determined that no collision has been detected in Step S10of FIG. 7, and the flow returns to Step S6 to repeat the same process.For example, in the case where the edge has been detected in the section(3) in the first collision determination, the second collisiondetermination is executed next time.

The degree of freedom of a design by users can be improved by variablysetting the gray section to the effective section or the destroysection.

Third Embodiment

In the above-described embodiment, the method of executing therestoration operation in accordance with an input of the collisioninterruption signal has been described. A method of executing arestoration operation with higher accuracy will be described.

Specifically, the collision detection circuit 307# generates collisioninformation together with the collision interruption signal to be outputto the restoration circuit 14.

The restoration circuit 14 executes the restoration operation on thebasis of the collision interruption signal and the collisioninformation.

FIGS. 13A, 13B, 13C and 13D are diagrams each describing an example inwhich a collision occurs in the middle of a bit on the basis of a thirdembodiment.

With reference to FIGS. 13A, 13B, 13C and 13D, examples of atransmission signal, a reception signal (normal), a reception signal(collision), and a collision interruption signal are shown.

With reference to FIG. 13A, a case in which data “0” has been output astransmission data is shown.

The reception signal in a normal condition falls in the section (3).

On the other hand, a case in which the reception signal in a collisioncondition falls in the section (0) is shown.

Then, a case in which the collision interruption signal is generated inresponse thereto is shown.

In this case, the collision information is generated together with thecollision interruption signal.

For example, as the collision information, information related to thelevel of the transmission signal at the time of detecting the collisionand the rise or fall of the edge of the reception signal, informationrelated to whether or not the collision determination arises from theedge, information related to the collision determination, andinformation related to the collision detection section are generated.

When the collision determination does not arise from the edge, no edgehas been detected and the section is the destroy section.

In the example, as the collision information, the transmission signal atthe time of detecting the collision is of the “H” level. The edge of thereception signal falls from the “H” level to the “L” level. Thecollision determination arises from the edge. The collisiondetermination is the first collision determination. The collisiondetection section is the section (0).

The collision arises from a normal data collision.

With reference to FIG. 13B, a case in which the data “0” has been outputas transmission data is shown.

The reception signal in a normal condition falls in the section (3).

On the other hand, a case in which the reception signal in a collisioncondition falls in the section (2) is shown.

Then, a case in which the collision interruption signal is generated inresponse thereto is shown.

In this case, the collision information is generated together with thecollision interruption signal.

In the example, as the collision information, the transmission signal atthe time of detecting the collision is of the “L” level. The edge of thereception signal falls from the “H” level to the “L” level. Thecollision determination arises from the edge. The collisiondetermination is the first collision determination. The collisiondetection section is the section (2).

Although the reception signal in a normal condition falls in the section(3), the reception signal falls before the section (3). Accordingly, thecollision arises from not delay of data but a normal data collision.

With reference to FIG. 13C, a case in which data “1” has been output astransmission data is shown.

Further, the reception signal in a normal condition rises in the section(3).

On the other hand, a case in which the reception signal in a collisioncondition rises in the section (4) is shown.

Then, a case in which the collision interruption signal is generated inresponse thereto is shown.

In this case, the collision information is generated together with thecollision interruption signal.

In the example, as the collision information, the transmission signal atthe time of detecting the collision is of the “H” level. The edge of thereception signal rises from the “L” level to the “H” level. Thecollision determination arises from the edge. The collisiondetermination is the first collision determination. The collisiondetection section is the section (4).

Although the reception signal in a normal condition rises in the section(3), the reception signal rises after the section (3). Accordingly,there is a high possibility that the collision arises from delay ofdata. Thus, it can be determined that no collision has occurred.

With reference to FIG. 13D, a case in which the data “1” has been outputas transmission data is shown.

Further, the reception signal in a normal condition rises in the section(3).

On the other hand, a case in which the reception signal in a collisioncondition does not rise even after the section (5) is shown.

Then, a case in which the collision interruption signal is generated inresponse thereto is shown.

In this case, the collision information is generated together with thecollision interruption signal.

In the example, as the collision information, the transmission signal atthe time of detecting the collision is of the “H” level. The edge of thereception signal is not generated, and thus is invalid. The collisiondetermination does not arise from the edge. The collision determinationis the first collision determination. The collision detection section isthe section (5).

Although the reception signal in a normal condition rises in the section(3), no rise is detected. Accordingly, the collision arises from a datacollision.

FIG. 14 is a flowchart for describing a restoration process on the basisof the third embodiment.

With reference to FIG. 14, the process is mainly executed by therestoration circuit 14 of the controller 10.

The restoration circuit 14 determines whether or not the collisioninterruption signal is present (Step S40).

Specifically, the restoration circuit 14 determines whether or not aninput of the collision interruption signal from the collisiondetermination circuit 13 is present.

In the case where the restoration circuit 14 determines that an input ofthe collision interruption signal from the collision determinationcircuit 13 is present in Step S40 (YES in Step S40), the collisioninformation is confirmed (Step S60). The restoration circuit 14 confirmsthe content of the collision information output from the collisiondetection circuit 307#.

Next, the restoration circuit 14 determines whether or not the collisionhas occurred in the destroy section (Step S62). The restoration circuit14 confirms the above-described collision detection section to determinewhether or not the collision has occurred in the destroy section. In thecase of FIG. 13D, the collision detection section is the section (5),and is determined as the destroy section.

Next, in the case where the restoration circuit 14 determines that thecollision has occurred in the destroy section (YES in Step S62), thetransmission is stopped (Step S63). The restoration circuit 14 stops thetransmission of data to the bus BS1 through the DALI communicationinterface module 4.

Next, the restoration circuit 14 outputs data of the “L” level to thebus BS1 through the DALI communication interface module 4 (Step S44).

Then, the restoration circuit 14 waits for a predetermined period in thestate (Step S46).

Accordingly, a collision of transmission data of the other controllers10 that are the other masters occurs, and the occurrence of thecollision of the other controllers 10 that are the other masters on thebus BS1 is detected.

Then, the same process is executed.

Next, the restoration circuit 14 outputs data of the “H” level to thebus BS1 through the DALI communication interface module 4 (Step S48).

Next, the restoration circuit 14 determines whether or not a receptionsignal from the bus BS1 through the DALI communication interface module4 is of the “H” level (Step S50).

In the case where the restoration circuit 14 determines that thereception signal is of the “H” level in Step S50 (YES in Step S50), itcan be determined that data of the “L” level has not been output fromthe other controllers 10 that are the other masters.

Next, the restoration circuit 14 clears the collision information (StepS52).

Then, the restoration circuit 14 executes the restoration operation(Step S54). Specifically, the transmission of data from the controller10 is started again. It should be noted that in order to suppress acollision of data with the other controllers 10 at the time of therestoration operation, the restoration operation may be started afterfurther waiting for a predetermined period.

Then, the process is completed (end).

On the other hand, in the case where the restoration circuit 14determines that the reception signal is not of the “H” level in Step S50(NO in Step S50), it can be determined that data of the “L” level hasbeen output from the other controllers 10 that are the other masters. Inthis case, the restoration circuit 14 waits until the reception signalbecomes the “H” level.

Then, the restoration circuit 14 waits until the reception signalbecomes the “'H” level in Step S50. After the reception signal becomesthe “H” level, the above-described restoration operation is executed.

Then, the process is completed (end).

On the other hand, in the case where the restoration circuit 14determines that no collision has occurred in the destroy section in StepS62 (NO in Step S62), it is determined whether or not a collision hasoccurred (Step S64). In the case of FIGS. 13A, 13B, and 13C, thecollision detection sections are the sections (0), (2), and (4),respectively, and thus are determined as not the destroy sections butthe gray sections. Then, it is determined on the basis of the collisioninformation whether or not the collision has occurred.

In the case where it is determined that the collision has occurred inStep S64 (YES in Step S64), the transmission is stopped (Step S65). Therestoration circuit 14 stops the transmission of data to the bus BS1through the DALI communication interface module 4.

Next, the restoration circuit 14 determines whether or not a receptionsignal from the bus BS1 through the DALI communication interface module4 is of the “H” level (Step S68).

In the case where the restoration circuit 14 determines that thereception signal is of the “H” level in Step S68 (YES in Step S68), itcan be determined that data of the “L” level has not been output fromthe other controllers 10 that are the other masters.

Next, the restoration circuit 14 clears the collision information (StepS70).

Then, the restoration circuit 14 executes the restoration operation(Step S74). Specifically, the transmission of data from the controller10 is started again. It should be noted that in order to suppress acollision of data with the other controllers 10 at the time of therestoration operation, the restoration operation may be started afterfurther waiting for a predetermined period.

On the other hand, in the case where the restoration circuit 14determines that the reception signal is not of the “H” level in Step S68(NO in Step S68), it can be determined that data of the “L” level hasbeen output from the other controllers 10 that are the other masters. Inthis case, the restoration circuit 14 waits until the reception signalbecomes the “H” level.

Then, the restoration circuit 14 waits until the reception signalbecomes the “H” level in Step S68. After the reception signal becomesthe “H” level, the above-described restoration operation is executed.

On the other hand, in the case where it is determined that no collisionhas occurred in Step S64 (NO in Step S64), the collision information iscleared (Step S76).

Then, the process is completed (end).

In the case of FIGS. 13A, and 13B, the collision detection sections arethe sections (0) and (2), respectively, and it is determined on thebasis of the collision information by the process that the collision hasoccurred. In this case, the transmission is stopped. Thereafter, in thecase where it is determined that the reception signal is of the “H”level, the restoration operation is executed.

Further, in the case of FIG. 13C, it is determined that no collision hasoccurred. Thus, the transmission is not stopped.

Therefore, in the case where the collision interruption signal is input,it is properly determined on the basis of the collision informationwhether or not the collision has occurred, and a restoration operationwith high accuracy is executed. On the other hand, in the case where thecollision interruption signal is input and it is determined on the basisof the collision information that no collision has occurred, thetransmission is not stopped. Thus, the data communications can be stablycontinued.

Further, in the case where the collision has occurred in the graysection, there is a possibility that the collision has temporarilyoccurred. Thus, the occurrence of the collision of the other controllers10 that are the other masters on the bus BS1 is not detected byoutputting data of the “L” level. Accordingly, the restoration operationin the entire system can be executed at high speed.

Another Embodiment

In the description of the above-described example, a photocoupler isused as a component of a communication interface module. However, thepresent invention is not particularly limited to the component, but canbe similarly applied to a case in which, for example, iCoupler(registered trademark) is used instead of the photocoupler.

Apart of the above-described signal processing can be realized by anapplication program. Namely, an application that can be executed by thecontroller may be provided as a program in the embodiment. In this case,the program according to the embodiment may be incorporated as somefunctions (modules) of various applications executed on a computer.

The disclosure has been concretely described above on the basis of theembodiments. However, it is obvious that the disclosure is not limitedto the embodiments, but can be variously changed without departing fromthe scope thereof.

What is claimed is:
 1. A collision determination circuit, comprising: anedge detection circuit that detects change timing of a signalrepresenting data of a command signal transmitted to a light sourcecontrol device; an area setting circuit that sets a plurality ofcollision determination areas in accordance with the change timingdetected by the edge detection circuit; and a collision detectioncircuit that detects the presence or absence of a collision of the dataof the command signal with other data in the plurality of collisiondetermination areas.
 2. The collision determination circuit according toclaim 1, wherein the area setting circuit includes a register forsetting a parameter to set a range of each collision determination area.3. The collision determination circuit according to claim 1, wherein thearea setting circuit sets the collision determination areas and a datadetection area where the data is normally detected.
 4. The collisiondetermination circuit according to claim 3, wherein the area settingcircuit sets the collision determination areas, the data detection area,and a variable area that can be set to any one of the collisiondetermination areas and the data detection area.
 5. The collisiondetermination circuit according to claim 1, wherein the plurality ofcollision determination areas includes a first determination area and asecond determination area, and wherein a restoration circuit executes afirst restoration operation in a case where the collision has occurredin the first determination area, and executes a second restorationoperation in a case where the collision has occurred in the seconddetermination area.
 6. The collision determination circuit according toclaim 1, wherein the area setting circuit sets a first collisiondetermination area in case that the change timing detected by the edgedetection circuit corresponds to a bit boundary, and a second collisiondetermination area in case that the change timing detected by the edgedetection circuit corresponds to a middle of a bit.
 7. The collisiondetermination circuit according to claim 6, wherein the area settingcircuit is further configured to set a plurality of first collisiondetermination areas and a plurality of second collision determinationareas.
 8. A light source control system, comprising: a plurality oflight sources; and a plurality of corresponding light source controldevices configured to communicate with each other through a bus, whereinthe light source control devices include a plurality of main lightsource control devices that transmit command signals to the other lightsource control devices, wherein each of the main light source controldevices includes a collision determination circuit that determineswhether data of the command signal transmitted through the bus hascollided with other data, and wherein the collision determinationcircuit includes an edge detection circuit that detects change timing ofa signal representing the data of the command signal; an area settingcircuit that sets a plurality of collision determination areas inaccordance with the change timing detected by the edge detectioncircuit; and a collision detection circuit that detects the presence orabsence of a collision in the plurality of collision determinationareas.